A low-budget surface slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently
brought into operation at the Advanced Light Source Optical Metrology Laboratory [Nucl. Instr. and Meth. A 616, 212-
223 (2010)]. The instrument is based on a precisely calibrated autocollimator and a movable pentaprism. The capability
of the DLTP to achieve sub-microradian surface slope metrology has been verified via cross-comparison measurements
with other high-performance slope measuring instruments when measuring the same high-quality test optics. In the
present work, a further improvement of the DLTP is achieved by replacing the existing bulk pentaprism with a specially
designed mirror based pentaprism. A mirror based pentaprism offers the possibility to eliminate systematic errors
introduced by inhomogeneity of the optical material and fabrication imperfections of a bulk pentaprism. We provide the
details of the mirror based pentaprism design and describe an original experimental procedure for precision mutual
alignment of the mirrors. The algorithm of the alignment procedure and its efficiency are verified with rigorous ray
tracing simulations. Results of measurements of a spherically curved test mirror and a flat test mirror using the original
bulk pentaprism are compared with measurements using the new mirror based pentaprism, demonstrating the improved
performance.

The long trace profiler (LTP) at SPring-8 has been fully upgraded in-house. The environmental temperature and air
pressure supplied to the air bearing were stabilized. An intensity-stabilized He-Ne laser, air-bearing slider, optical
elements, and a detector were replaced to improve the stability and resolution of slope measurement. The newly
installed device, a motorized swivel stage, enables automatic stitching measurements. Two steep mirrors whose range of
slope is wider than the angular range of the LTP were measured by using the stitching technique.

The Diamond-NOM is a non-contact, slope measuring profiler, capable of measuring surface topography of large optics
(up to 1.5m long) with sub-nanometre height resolution and repeatability. On numerous occasions, the Diamond-NOM
has proven to be an invaluable metrology tool for independently validating new beamline optics, and for investigating
potential problems with optics from established beamlines. Data from the Diamond-NOM have consistently been in
close agreement with results generated by a range of metrology instruments at other synchrotron laboratories and optic
manufacturers. Prior to beamline installation, significant X-ray commissioning time was saved by optimizing and
calibrating adaptive optics using the Diamond-NOM. We report on the current operational capabilities of the Diamond-
NOM and give technical details of recent upgrades, including a penta-mirror (two, high grade reflectors used to mimic
the internal working surfaces of a traditional pentaprism) and the capability to measure optics in sideward, downward, or
upward facing geometries.

Brightness preservation requirements for ever brighter synchrotron radiation and free electron laser beamlines require
surface slope tolerances of x-ray optics on the order of 0.2 μrad, or better. Hence, the accuracy of dedicated surface slope
metrology must be 0.1 μrad, or even less. Achieving this level of measurement accuracy with the flagship instrument at
synchrotron radiation metrology laboratories, the Long Trace Profiler (LTP), requires all significant sources of
systematic, random, and instrumental drift errors to be identified, and reduced or eliminated. In this respect, the
performance of certain components of the Advanced Light Source LTP-II design [Kirschman, et al., Proc. SPIE, 7077,
70770A-12 (2008)] is analyzed, considering the principal justification for inclusion of each component, possible
systematic error due to the quality of its optical material, and drift effects due to generated heat, etc. We investigate the
effects of replacement of the existing diode laser with a fiber-coupled laser light source, and demonstrate that reducing
the number of components by using a single beam on the surface under test (SUT), rather than an original double beam
maintains, or even improves the accuracy of measurement with our LTP. Based on the performance of the upgraded
LTP, we trace the further steps for improving of the LTP optical system.

The ESRF has initiated an ambitious ten-year upgrade program involving the construction of eight new beamlines and
significant refurbishment of existing instruments. The availability of high-precision X-ray optical elements will be a key
factor in ensuring the successful implementation of these beamline projects. Particular challenges are to ensure the
necessary optical quality for X-ray beam coherence preservation and high numerical-aperture high focusing systems.
Surface optical metrology is a key tool, not only for the quality control, but also in improving the manufacturing
processes of such components. Amongst the most demanding tasks is the characterisation of the surface topography of
highly aspheric surfaces for reflective nanofocusing technologies which typically require measurement of shape errors in
the nm range.
In order to satisfy these new demands, the ESRF metrology laboratory has recently been equipped with two new
instruments: a Fizeau interferometer and a micro-interferometer. In parallel the long trace profiler has been continuously
developed to increase both stability and accuracy.
In this paper we will present the new instrumentation and associated techniques like micro-stitching interferometry used
to measure typical high quality X-ray mirrors.
We will also focus on the parameters that can affect repeatability and accuracy of the radius of curvature assessment of
flat optical surfaces, in particular when measuring with the long trace profiler. Finally an example of the power spectral
density function based on our instrument measurements of a typical high quality x-ray mirror will be shown.

Power Spectral Density (PSD) is an alternative method for specifying optical surfaces, and quantifies the contribution of
each spatial regime to the total surface error. This approach naturally includes mid-range spatial frequency errors, which
are often overlooked. The PSD method has recently been adopted by the Space and Astronomy industries, but has not yet
received general acceptance within the synchrotron community. To assess the suitability for specifying synchrotron
optics using PSD, Fast Fourier Transforms were performed on topography data from a range of optical surfaces of
varying quality and manufacturing techniques. For each grade of optic, the entire regime (~100nm to ~50mm) of surface
errors was measured, with overlapping bandwidths, using a micro-interferometer and a Fizeau interferometer. From this
heuristic information, root-mean square "roughness" can be predicted over any desired spatial range, thus allowing direct
comparison of metrology data obtained by instruments with different spatial bandwidths. We present an efficient
approach for calculating 1-D and 2-D PSDs using MATLAB algorithms, and discuss analysis considerations, including
"field of view" effects and instrument calibration.

A laser Fizeau interferometer system has been developed to characterize the figure error of large synchrotron X-ray
mirrors using double-pass geometry. This opto-mechanical assembly comprises integrated rotation and translation stages
to control: the output angle of the Fizeau interferometer; the surface normal of the optic under test; and the orientation of
a high quality (λ/100) retro-reflector. To negate the effects of gravitational deformations, the system can measure long
optics (up to 1.5m in length) in the geometry (sideward, downward, or upward facing) in which they will ultimately be
used on a synchrotron beamline. The system has been designed to minimize environmental noise and enable the
measurement geometry to be changed quickly and safely. Compared to complementary techniques, including slope
profilers such as the Diamond-NOM, surface height data from the Fizeau system can be obtained more rapidly (<1
minute). This makes the technique ideally suited to investigate the many degrees of freedom of adaptive optics, including
piezo bimorph mirrors. The shape of such optics can also be monitored in real time to observe the dynamic effects of the
surface in response to applied voltages. Results are presented to illustrate system performance, including repeatability
levels. Calibration of the reference surfaces and the required environmental conditions are also discussed.

A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays
[Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)] has been proven to be an effective MTF calibration
method for a number of interferometric microscopes and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010].
Here we report on a significant expansion of the application range of the method. We describe the MTF calibration of a
6 inch phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests
with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally
limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering
procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for
calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a
multilayer structure with the layer thicknesses of two materials corresponding to BPR sequence. The investigations
confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation
with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

Periodic multilayer KB microscopes have widely implemented in x-ray diagnostic experiments of ICF, especially at relatively high x-ray energies (8keV or higher). But the obvious disadvantage, due to narrow bandwidth of periodic multilayer, is the ununiformity of x-ray image brightness and the limited field of view. The literature describes the characterization of a high-energy KB microscope with aperiodic multilayer configured to achieve larger effective field of
view than existing periodic multilayer KB microscopes. The microscope, working on 8keV with grazing angles of 1.1330° and 1.1837°, is capable of 5μm resolution over ±200μm object field. Design of the multilayer and experimental results with a Cu x-ray tube will be shown.

Nano-focusing and brightness preservation for ever brighter synchrotron radiation and free electron laser beamlines
require surface slope tolerances of x-ray optics on the order of 100 nrad. While the accuracy of fabrication and ex situ
metrology of x-ray mirrors has improved over time, beamline in situ performance of the optics is often limited by
application specific factors such as x-ray beam heat loading, temperature drift, alignment, vibration, etc. In the present
work, we discuss the recent results from the Advanced Light Source developing high accuracy, in situ, at-wavelength
wavefront measurement techniques to surpass 100-nrad accuracy surface slope measurements with reflecting x-ray
optics. The techniques will ultimately allow closed-loop feedback systems to be implemented for x-ray nano-focusing. In
addition, we present a dedicated metrology beamline endstation, applicable to a wide range of in situ metrology and test
experiments. The design and performance of a bendable Kirkpatrick-Baez (KB) mirror with active temperature
stabilization will also be presented. The mirror is currently used to study, refine, and optimize in situ mirror alignment,
bending and metrology methods essential for nano-focusing application.

Image degradation due to scattered radiation form residual optical fabrication errors is a serious problem in many
short wavelengths imaging system. Most currently-available image analysis codes require the bidirectional
scattering distribution function (BSDF) data as an input in order to calculate the image quality from such systems.
This BSDF data is difficult to measure and rarely available for the operational wavelengths of interest. Since the
smooth-surface approximation is often not satisfied at these short wavelengths, the classical Rayleigh-Rice
expression that indicates the BSDF is directly proportional to the surface PSD cannot be used to calculate BSDFs
from surface metrology data for even slightly rough surfaces. An FFTLog numerical Hankel transform algorithm
enables the practical use of the computationally intensive Generalized Harvey-Shack surface scatter theory to
calculate BRDFs for increasingly short wavelengths that violate the smooth surface approximation implicit in the
Rayleigh-Rice surface scatter theory. A generalized Peterson analytical scatter model is then used to make accurate
image quality predictions. The generalized Peterson model is numerically validated by both ASAP and ZEMAX.

This article presents the design and simulated performance of a two-dimensional x-ray shearing interferometer
wavefront sensor. In particular, this phase sensitive x-ray wavefront sensor is evaluated for its ability to perform
metrology on the DT ice layer in an inertial confinement fusion capsule. The interferometer uses crossed phase gratings
in a single plane and is capable of operation over a wide range of x-ray energies by varying the grating material and
thickness. The wave-front sensor is insensitive to vibrations and, unlike X-RayTalbot interferometers, recovers the full
two-dimensional phase profile of the x-ray beam rather than the gradient in only one dimension.

A Schwarzschild microscope at 18.2 nm for ultra-fast laser plasma diagnostics has been developed.
Based on the third-order aberration the microscope is designed for numerical aperture of 0.1 and
magnification of 10. Spatial resolution of the objective can achieve 1250 lp/mm within the field of ±1
mm. Mo/Si multilayer films with peak throughout at 18.2 nm is designed and deposited by magnetron
sputtering, and the measured reflectivity of optical elements is 45%. The 600 lp/inch copper grid
backlit by laser produced plasma is imaging via Schwarzschild microscope on CCD. The spatial
resolution is measured as 3 μm approximately in the field of 1.2 mm.

Fizeau interferometer is the most commonly used interferometer for testing optical components. The aim of this work is
to apply this technique to the measurement of elliptical Kirkpatrick-Baez (KB) mirrors during their fabrication process.
KB mirrors are widely used at synchrotron radiation facilities around the world for x-ray focusing. Fizeau interferometer
can provide accurate measurements for KB mirrors. Recently a KB mirror that can focus X-ray down to 150 nm has
been fabricated in the Argonne National Laboratory.

The surface profile of Wolter type-I mirror has a great impact on the performance of Solar X-ray Telescope. According to the existing fabrication instrument and experimental conditions in our lab, an
in situ Long Trace Profiler is developed and set up on the fabrication instrument in order to measure the surface profile of Wolter mirror in real time during fabrication process. Its working mechanism, structural parameters and data processing algorithm are investigated. The prototype calibrated by a standard plane mirror is used to measure a sample of Wolter type-I mirror. The results show that our prototype can achieve an accuracy of 2.6μrad rms for slope error with a stability of 1.33μrad during the whole measurement period. This can meet further fabrication requirements.

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